PURPOSE: To perform high-grade printing at a fast speed by discriminating the kind of data to be printed, for example, whether the data to be printed is document data or image data and automatically setting the optimum printing mode from a plurality of prepared printing modes on the basis of the discriminated result.

CONSTITUTION: When data to be printed is document data, for example, a mode setting means 3 sets printing density 'ordinary' mode and a printing speed 'ordinary' mode as printing modes. A printing means 4 prints the document data in a printing data memory means 1 according to the printing modes set by the mode setting means 3. When the data to be printed is image data, for example, the mode setting means 3 sets a printing density 'high' mode and a printing speed 'slow' mode as printing modes. The printing means 4 prints the image data in the printing data memory means 1 according to the printing modes set by the mode setting means 3. Therefore, the data can be printed according to the optimum printing modes corresponding to the kind of the data to be printed.